Safety control system foe fluid



SAFETY CONTROL SYSTEM FOR FLUID FUEL -BURNERS Filed oct. 1, 1935 2 sheets-sheet 1 l2 I3 J iNl/ENTOR.

IRA E'. MIE/456' BY M A TTORNE Y.

Sept. 5, 1939. l, E. MccABE v 2,171,858'

SAFETY CONTROL SYSTEM FOR FLUID FUEL BURNERS l Filed om. 1 1935 2 sheets-sheet 2 INVENTOR. IRA BJMQLZABB x FIG. E ATTORNEY.

- changes may be made without Patented Sept. 5, 1939 SAFETY CONTROL SYSTEM 4FOR FLUID FUEL B URNERS Ira. E. McCabe, Chicago, Ill. Application October-` 1, 1935, Serial No. 43,075

solenne (c1. 15s- 117.1)

This invention relates to a safety controln system for Vfluid fuel burners and more particularly to a burner of this type` in which the fuelv is ignited by a pilot light.

'There is on the market at the present tim a gas burner for warm air heaters provided with a continuously burning gas pilot mounting a reciprocable actuator rod responsive to the presence or absence of heat of saidpilot in conjunction with an electric switch in a circuit for controlling an electrically operated valve in the gas supply to the burner. Itis an object of this inply upon the extinguishing upon the reversing of fthe of the pilot light and other manual switch to establish a circuit in seriesv with the pilot light controlled circuit to to the burner. Said latter open the gas supply circuit may be controlled by a switch responsive to the temperature within the heater whereby the burner may be supplied with fuel intermittently as long as the pilot light-is burning but shut off immediately the pilot becomes extinguished and require-,a manual operation of the two switches before .the

burner can again operate.

The reversal of said manual switch to control the gas supply may, if 'so desired, establish at the same time a p arallel circuit to operate a motor driven fan blower.

While the embodiment of this invention disclosed herein is designed as a safety control for a gas fired warm air heater such' as may be 1ocated in the space or room wherein the heat isV desired and people are present and therefore extremely hazardous should unburnt gas escape or be present when attempts were made to re-lignt an extinguished pilot, its application to any fluid 'fuel burner ignited by a pilot is obviously within the scope thereof.

With these and other objects in view, reference is made to the accompanying sheets of draw'" ings, illustrating an embodiment 'of this invention with the understanding that minor detail the scope thereof.L

In the drawings- Figure 1 is a wiringtdiagr departing from 'x' lof thejcontrol circuits indicating in full lines the path of the current when both manual switches are first closed.

y Figure 2 is a similar diagram indicating in full lines the path ofthe current-after the switch responsiveto the heat of the pilot has closed 5 and one of the manual switches opened.

.Figure 3 is a similar diagram illustrating the path of the current after the second manual switch has been reversed with the thermostatic switch responsive to the temperature of the 10 heater 'closed as in normal operation. f

Figure 4 is a view in elevation of the bracket supporting one end of the actuator rod responsive to the presence or absence of heat from the burning pilot and the covered switching 15 mechanism operated thereby.

Figure 5 is an enlarged detail top plan view of the switching mechanism, with the cover and mercury tube switch removed.

Figure 6 is aview in front elevation of AFigure- 20 5 with the tube clip removed and the magnet arm carrying sleeve shown partly in section.

Figure '7 is a. view in side elevation of Figure 5 looking thereon from the right.

Figure 8 is a similar View looking thereon from 25 the left.

Figure 9 is a detail view in elevation of the pilot responsive thermal member.

In the diagrammatical viewsshown in Figures 1, 2 and 3,v a normally closed thermostatic switch 30 T of commercial .construction is located within the warm air heater, not shown, and is responsive to the temperature therein. A three-way switch K is normally located within the vicinity of the heater. A normally open momentary 35 y contact pu'sh button switch` P ispreferably l'ocated in the vicinity of the opening in the warm air heater for lighting the gas pilot GP. When Athe switch K is manually thrown to the uppermost closed position, as shownin Figure l, and 40 the switch -P closed, a circuit is completed through the wire L from the commercial line, or-other source of electricity, through the lpush button switch P, the wire |binding post 2 of switch K, through switch K to binding post 3 45 thereof,'thence through wire 4 to lower binding post 5 of switch K and from thence by wire 6 throughl the windings .of a solenoid operated valve -V in the gas supply pipe PS to the pilot button switch P is normally open and no gas can be supplied to thepilot light burner, so that when I, it is desired to ignite the pilot it is necessary to j n rst manually close 'the switch lK, as shown vinl` Figure 1, and then depress the push button switch P while the pilot light is being ignited by a match or other ame.

The heat from the burning pilot GP, through ameans hereinafter described, closes the switch S. The actuating means is responsive to the presence or absence of the flame of the pilot and is adapted to open or close the switch S, as the case may be, in an adjustable period ranging from 11/2 to 10 seconds. The closing of the switch may thus be said to be immediate with the establishment or failure of the flame.. Upon the closing of the switch S, a circuit is established by wire 1 from the lead L through theclosed switch S, wire 8, binding post 5 of the lower position of the switch K and wire 6 through the solenoid windings of valve V in the return lead L'. It is therefore seen that as long as the pilot light is burning the push button switch P may return to its normally open position and the solenoid will remain energized to hold open the valve V to supply gas tolthe pilot but should the pilot become extinguished before the burner' B is ignited the switch S will open said circuit and the valve V will close preventing gas from escaping through the pilot burner. This circuit is illustrated in Figure 2.

After the pilot light has necessary to manually throw the knife switch K into its lowermost position, as shown in Figure 3, in order to ignite the burner flame. When the switch K is in its lowermost position, a circuit is established from binding post 5 through switch K to binding post 9 and by wire I0 through the normally closed thermal switch T and Wire II through the windings of the solenoid or motor operated valve G in the gas supply pipe FS to the burner land thence to the return line L'. It is to be noted here that the main valve G controls only the fuel supply FS for firing the heater and that the pilot` valve V is connected in the supply line ahead of the valve G. The closing of switch K in its lowermost position therefore establishes a circuit -through the pilot light switch S to binding post 5 and through both valves V and G to maintain the valve V open to supply gas to the pilot GP and to open and hold open the valve G to supply gas to the burner B. When the temperature within the heater reaches the degree set to open the thermostatic switch T the valve G will be vclosed while the valve V will remain open so that when the temperature within the heater descends below the setting of the thermostat T, the valve G will be opened and the burner flame ignited by the continuously burning pilot, whereby the valve G may be intermittently operated as long as the pilot is burning. Should the pilot become extinguished at any time during the operation of the heater burner, the circuit therethrough will be broken which will also break the circuit to the valve G and the burner cannot be again ignited until the switch K is manually thrown'to its uppermost position, the push button P be depressed and the pilot ignited. In warm air heaters, it is desirable to have a circulating fan operated by a motor, such as the motor M shown in the said diagram. In order that the motor may be operated while the burner is in operation, one pole of the motor is connected to binding post 9 by wire I2 and the other pole by wire I3 to the return lead L'.

From the above description it is seen that this system provides a safe system at all times, the features of which are:

l. The entire system is shut down immediately 'upon failure of the pilot flame.

been ignited, it is" This insures against the circulation for any extended length of time `of unburned gas and prevents the accumulation of gas within the heater which would explode when attempts were made to re-light the pilot flame.

2. Requires the manual operation of two being a double throw type and the other of the type which automatically opens` when not manually held closed. The double throw switch when operated to prepare the circuit by which the other switch opens the pilot valve, breaks the circuit to the main gas valve. It is thus assured that the main valve cannot be opened during the lighting of the pilot flame to fire the burner and possibly burn the person engaged in the lighting.

3. Requires the manipulation of the double throw switch after ignitlng the pilot flame to place the main gas valve in control of the thermostat as long as'- the pilot flame continues to burn. Operation of the burner, therefore, depends upon the continuous burning of the pilot flame and ends substantially with the extinguishment thereof.

4. While it is necessary to actuate the manual switches in the prescribed sequence when placing the burner in operation, failure to do so while not accomplishing the desired results will neither rethe burner. Thus protection is afforded at all timeswhile the burner is in or out of operation or during the process of placing it in operation.

It is obvious that this system may be applied to any electrically operated and controlled fluid fuel burner employing gas ignition by simply controlling the burner mechanism through the thermostat T.

As heretofore stated, the switching mechanism for opening and closing the switch S is responsive to the presence or absence of a flame at 'thekpilot, and the mechanism illustrated in Figures 5 to 8, inclusive, is an improvement of a device now on the market including a horse shoe thermal element such as disclosed in the application of O. W. Hahn, Serial No. 624,505, led July 25, 1932 which matured into Patent No. 2,064,909 of December 22, 1936, which is provided With means for reciprocating an actuating rod through a casing to the switch operating mechanism extending said rod when the pilot is burning and withdrawing said rod when the pilot is extinguished which means includes attaching to the end of the rod adjacent the pilot a strip of metal readily expandible in the presence of heat and readily contractible as soon as the heat is removed. This preferred means for reciprocating an actuating rod is shown in Figure 9.

In Figure 4, a bracket Ilis shown supporting a base plate I5 and a sleeve I6 extending in the opposite direction which surrounds a reciprocating actuating rod I1 operated in the manner hereinbefore described. In this figure, a cover I8 is shown surrounding the improved switching mechanism and attached to the base I5. A switch supporting bracket having a horizontal portion I9 and a depending right angular portion 20 extending from one end is secured to the base I5 by screws 2l with the horizontal portion arranged centrally above the portion of the actuating rod Il passing through the base I5 with the portion 20 provided with an outstanding right angular 75 member 22. The member 22 supports a. switch carrying clip 23 for engaging a tube switch 24 between resilient arms 25 formed integral withsaid clip 23. The mercury tube switch 24 is of the switch, the other termina 2s ,of which is resiliently mounted and normally assumes a position out of contact with the mercury, said latter terminal being provided with an armature 2B of magnetic metal adapted to be drawn to the adjacent side of the tube by the inuence of a magnetic eld of a magnet to cause the terminal 28 to contact the mercury 26 and close the circuit through the switch, such a switch construction being disclosed in the prior copending application, Serial No. 665,628, filed April 12, 1933, which matured into Patent No. 2,085,316, granted June 29, 1937.

A xed magnet 30 is mounted upon a right angular extension 3| at the lower end of an arm 32 secured to a sleeve 33 rotatably mounted upon a bearing 33a which in turn is mounted upon a reduced portion at one end of the shaft 34 carried upon a right angular extension 35 of a bracket 36. A spring 31 normally tending to cause rotationA of the arm 32 to move the magnet 36 to contact the adjacent wall of the mercury tube switch 24 is'mounted at its upper end 38 by rivets 39 to the horizontal arm I9 of the switch supporting bracket. The bracket 36 is mounted upon the upper portion 38 of the spring 31 by rivets 4D with the top of the bracket 36 approximately in line with the under side of the bracket portion I9. y

The portion 22 of the switch carrying'bracket is provided at its lower end adjacent the base |5 with a right angular portion 50 extending from the side opposite the mercury tube switch 24 which portion mounts' screw threaded adjustable stops 5i and 52 one above the other with the lower stop 52 provided with a member 52a carried parallel to the base I5 and extending in the direction of the stop 5|. A stop arm 54 secured to a sleeve 53 mounted on the end of vthe shaft 34 opposite the magnet arm is provided with an extension 54a which extends between the stop 5| and the extension 52a of the stop 52 whereby the oscillating movement of said arm may be adjustably limited.

The sleeve 53 of the stop arm 54 is provided with a shoulder having a sliding engagement with the surface of the portion 35 of the bracket 36 and is held in frictional contact therewith by a coiled spring 46 surrounding the sleeve 53 and bearing at one end against said shoulder and at the other end against the magnet arm bearing which bears against a washer disc 41 held in position by a nut 48 threaded upon the screwthreaded end 49 of the reduced portion of the shaft 34.

In order that the magnet arm will move with the stop arm 54, as movement is imparted to the bracket 36 by the spring 31 the stop arm is provided with a second extension 54b in the form of a flat spring extending in the direction of the magnet arm and adapted to contact the edge of said arm under tension. The extension 54h not only keeps Vthe magnet arm in alignment with the stop arm 54 and causes arm 32 to move with arm 54h but also restores the magnet to its proper position when it is moved as a result ofl the device being struck or jarred which shocks, Without the spring extension 54D, would cause the magnet arm with the weight of the magnet carried. beneath it, to creep toward the mercury switch 24 and close the circuit therethrough. 4

The actuating rod I1 passes through` apertures provided therefor in the base l5, .portion 38 of the spring 31 and bracket 36 and is reciprocably4 mounted therein. The end of the actuatingrod 1 is provided with a rcubical member 4| axially drilled upon a diameter to vengage therod and the exterior end of the actuating rod is provided with a lock nut 42 having a plurality of similar oppositely disposed parallel faces each ofwhich are provided with a central groove 43 adaptedto engage one of the transverse edges of 'the cubicalmember 4| to lock the nut. To maintain the opposite transverse edge horizontal in a position to form a knife vedge engagement with a V groove 36a in the bracket 36 a distance below the top thereof, the cubical member 4| is provided with a stud 44 extending axially from one side thereof and the portion 35 of th-e 'bracket 36 is provided with a notch 45 to receive the stud 44 to prevent rotation of the member 4| and at the same time to allow a back and forth movement thereof.

The cubical member 4| is so adjusted upon the actuator rod I1 that when the pilot is extinguished so that the rod |1 is at the end of its travel away from the switching mechanism the transverse edge of said member bears against the bracket 36 with sufcient force to bend the l spring 31 about the loweredge of the bracket I9 and cause the bracket 36 secured thereto, the shaft 34 mounted thereon, and the stop arm 54 and magnet arm 32 carried thereby to move the magnet 36 away from the switch 24 to break the circuit therethrough, and when the actuator rod is moved in the opposite direction by the heat of the burning pilot the spring 31 is freed to move the magnet 30 into contact with the switch 24 to close the circuit therethrough.

During this movement of the magnet 36 the extension 54a of the stop arm 54 reciprocates between the stops 5| and 52a upon the extension 56 of the switch carrying bracket portion 22 and as the magnet arm is caused to move with the stop arm 54 through the spring connection 56h,

l as previously described, the travel of the magnet may be adjustably limited thereby as the stop arm 54 is mounted for frictional engagement with the bracket 36 by the spring pressed sleeve 53 carrying said arm allowing continued movement of the bracket 36 after the arm has engaged a stop and at the same time causing immediate movement in Ithe opposite direction simultaneously with the slightest movement of the actuator rod l1 in the opposite direction.

In the embodiment of this invention as hereinbefore described, it is desirable that in igniting the pilot the said switching mechanism respond immediately so that it is -only necessary for a momentary closing of the push button switch P. By the construction illustrated in Figures 5 to 8, inclusive, the mechanism may be so adjusted that a movement of but .005 of an inch in either direction will operate the switch 24 within a minimum of 11/2 seconds to a maximum of 10 secondsfollowing the ignition of the pilot to establish the circuit to close the circuit therethrough to maintain the gas supply to the pilot.

Figure 9 represents the commercial device heretofore referred to which is responsive to the presence or absence of the pilot light for imparting movement to the actuating rod I1 which includes the horseshoe shaped thermal element in sleeve I6 to enter within the horseshoe, as shown.

rI"he other heel 59 of the horseshoe extends through an opening provided therefor in the upper side of the sleeve I6 and is attached to the end of the actuating rod I1. The toe of the horseshoe element is provided with a plurality of circular openings 60 which reduces the metal directly above the nozzle 51 of the pilot, so that as soon as the pilot is ignited the heat therefrom p immediately acts upon this reduced portion of the thermal member and from its shape will impart an immediate movement to the actuating rod I1. Likewise, immediately upon extinguishing the pilot a movement in the opposite direction will be imparted to the actuating rod. It has also been found advantageous to provide a -gude 6I for the resilient terminal 28 of the mercury tube switch 24, as shown in Figure '7. The guide 6| is welded or otherwise secured at its upper end to the rigid portion of the terminal 28 and is of approximately the same rigidity as said main portion with the lower end terminating in a coil B2 through which the lower end of the terminal 28 slides in the making and breaking of the circuit through the switch and prevents the spring carrying the armature 29 from being sprung and shifting the position of the terminal 28.

What I claim is:

1. A safety control system for a fluid fuel burner ignited by a flaming pilot including a source of electricity, a normally open automatic t switch connected thereto responsive to heat from the pilot flame to close to establish a circuit, an electrically operated valve in said circuit to control the flow of fuel to the pilot and operable while energized to allow the flow of fuel to the pilot, a shunt circuit around said heat responsive switch including said valve, and a normally open manually operated momentary contact switch, said switch adapted when closed to energize the said valve to supply fuel to the pilot for ignition, whereafter upon failure of the pilot flame the rst circuit is opened, a second manual switch adapted in one position to prepare the shunt circuit to said valve to be completed by closing the momentary contact switch, and adapted in another position after ignition of the pilot to establish a third circuit including the switch responsive to the heat of the pilot flame, and an electrically operated valve in said third circuit to control the flow of fuel to the burner, said switch in establishing the third circuit opens the shunt circuit.

2. The structure of claim 1 wherein a normally closed additional thermostatic switch adapted to open in response to heat from the burner is interposed in said third circuit to intermittently open and close the fuel supply valve to the burner as long as the pilot is burning.

3. Heating apparatus comprising in combination, a. main burner, a fuel supply pipe leading thereto. an electrically operated valve in said pipe operable to open said pipe when energized and;` to close said pipe when deenergized, an energizing circuit for said valve, a shunt circuit connected to said energizing circuit, manually operated means operable to energize. either said energizing circuit or said shunt circuit, a pilot burner in igniting proximity to said main burner, a thermostatic switch responsive to the heat of said pilot and located in said energizing circuit and operative to control said valve, and electrically operable means in said shunt circuit operatively associated with said pilot, the establishment of a flame at said pilot being dependent on the energization of said last named means.

4. A safety control system for fluid fuel burners ignited by a flaming pilot and including a pilot valve and a burner valve, consisting of a normally open automatic switch responsive to heat from the pilot to close, operating circuits for each of said valves with each circuit having in series therewith said automatic switch, an initial energizing circuit for the pilot valve, and manually operated means operable to energize either the burner valve operating circuit or the pilot Valveinitial energizing circuit, said circuits so controlled that upon energizing the pilot circuit the burner valve circuit is opened.

5. The structure of claim 4, wherein said initial energizing circuit for the pilot valve includes a manually operated momentary contact switch.

. IRA E. MCCABE. 

